Plate-type heat exchanger



I R. DICKSON PLATE-TYPEHEATZEXGHANGER Feb, 17, 1970 s Sheeis-Sheet 1 Filed March 15, 1968 FIG.

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United States Patent U.S. Cl. 165-166 11 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger having passageway openings of varying area from one passageway of a series to the next passageway of the series. Passageway openings are arranged to decrease flow of a hotter fluid or to increase flow of a cooling fluid towards the outermost passageways of the series.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to plate-type heat exchangers. In an exchanger of this type, a plurality of spaced apart plates define at least two series of passageways for containing heat exchange fluids, one heat exchange fluid for each series.

DESCRIPTION OF THE PRIOR ART In use of plate-type heat exchangers it is known that temperature induced stresses are imposed upon the plates because of the operating temperature differential of heat exchange fluids passing through the exchanger. The degree of stress is proportional to the temperature differential and this differential may be such that a sutficiently high degree of stress is obtained to result in failure in the plates or spacer bars between the plates. These failures tend to occur at or adjacent the outer plates or bars of an exchanger as the temperature induced stresses are normally higher in these plates than at plates lying intermediate the outer plates.

One way to reduce the incidence of failures is to completely blank off the passageway or passageways of one series between the outermost and the adjacent plates. It is found, however, that sufficiently high "temperature induced stresses may then be imposed upon intermediate plates to result in failure of these intermediate plates or of the spacer bars between them.

SUMMARY OF THE INVENTION According to the invention, a plate-type heat exchanger comprises a plurality of spaced-apart plates defining a first and second series of passageways, the first series being provided for the pasage therethrough of one heat exchange fluid and the second series for the passage therethrough of a relatively hotter heat exchange fluid with passageways of each series being interposed with passageways of the other series, and means in the first series or second series of passageways for controlling flow of fluid through the outermost passageways of each series, respectively, at a greater or lesser rate than through passageways intermediate the outermost passageways.

Preferably, in the first series of passageways, said means controls rate of flow of fluid so that the flow decreases progressively from passageway to passageway from each of the outermost passageways to a spaced intermediate passageway. It is also preferable, where the means is provided in relation to the second series of passageways, that said means controls the rate of flow of fluid so that 'ice the flow increases progressively from passageway to passageway from each of the outermost passageways to a spaced intermediate passageway.

In the first series of passageways, said means may be a member or members disposed in the outermost passageways and defining effective areas of passageway openings which are greater than effective areas of openings for fluid defined in the intermediate passageways so that fluid is allowed to pass at a greater rate through the outermost passageways. Alternatively, the means may be a member or members in each of the outermost passageways with a surface area for frictionally contacting fluid which is less than that of a member or members disposed in an intermediate passageway so that flluid is allowed to pass at a greater rate through the outermost passageways. With regard to the second series of passageways, the means may be a member or members disposed in the outermost passageways and defining effective areas of passageway openings which are less than efliective areas of passageway opening for fluid in the intermediate passageways or the member or members may have a surface area for frictionally contacting fluid which is greater than that of a member or members disposed in an intermediate passageway.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view of :a plate-type heat exchanger according to a first embodiment;

FIGURE 2 is an end view on a stack of plates of a plate-type heat exchanger according to a first embodiment;

FIGURE 3 is a view similar to FIGURE 2 of a second embodiment;

FIGURE 4 is a plan view of a member disposed within passageways of the exchanger as shown in FIGURE 3;

FIGURE 5 is a plan view of a corrugated member of the heat exchange of FIGURE 3, showing diagrammatically the positions of the corrugations;

FIGURE 6 is a View similar to FIGURE 2 of a third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first embodiment as shown in FIGURE 1, a heat exchanger comprises a series of spaced apart plates 1 separated by spacer bars 2 and defining a first series of passageways 3, and a second series of passageways 4. The passageways 4 are provided for the passage therethrough of a relatively hot fluid, while the passageways 3 are provided for a cooler fluid so that heat transfer takes place through the plates from the passageways 4 to the passageways 3. Fluid flow control means are provided in the outer passageways of the second series for controlling flow of fluid through the outermost passageways at a lesser rate than through the intermediate passageways. This means comprises a spacer bar 5 in each of the outermost passageways 4 (one only being shown in the respective drawings), each spacer bar extending across the inlet end of the passageway, The spacer bar 5 is provided with a plurality of passageway holes 6 to allow fluid to pass along the passageway from an inlet 15 to an outlet (not shown) at the opposite side of the exchanger. A spacer bar 7 is located in the next adjacent outer passageway 4 of the second series, the bar being provided with spaced apart passageway holes 8 of larger cross-section than the holes 6. Spacer bars are not provided extending across the inlets of intermediate passageways of the second series, which are simply provided with a corrugated secondary surface member 9 in known manner extending from one end of the passageway to the other. Corrugated secondary surface members are provided in the outer pas sageways behind the bars 5 and 7. The sizes of the holes 6 and 8 and of the openings provided by the corrugated members 9 are such that the effective area of passageway opening increases progressively from the outermost passageways 4 to the adjacent outer passageway and then to the first intermediate passageway. All of the passageways 3 are provided simply with secondary surface members of corrugated construction similar to the members 9 in the passageways 4 for the flow of fluid from an inlet 16 to an outlet (not shown) at the opposite side of the exchanger.

In use of the heat exchanger, the cool fluid passes through the passageways 3 in the direction of the arrows as shown while the relatively hot fluid passes along the passageways 4. As the effective areas provided by the holes 6 and 8 are less than the openings provided by the members 9, the flow of fluid through the holes '8 in less than that through the intermediate passageways of the second series and the flow of fluid through the outermost passageways 4 is less than that through the next adjacent outer passageway 4. There is, therefore, less heat to be transferred and thus less heat transfer from fluid in the outermost passageways 4 of the second series to the adjacent passageways 3 of the first series than between inner passageways of the two series 4 and 3. The heat to be transferred increases progressively from passageway to passageway of the series 4 from the outermost to the intermediate ones. Because of this, it is found that the temperature induced stresses in the outermost and next adjacent plates 1 are less than that which would be found if all of the passageways 4 had their greatest possible area of passageway opening. While in use, the intermediate passageways result in heat exchange efficiency which is substantially the same as that with a conventional exchanger for the same use, and the spacer bars 7 and 5 may be designed to allow suflicient of the hot fluid through the outer passageways to ensure that the stresses induced in the plates by virtue of the temperature differential are insufiicient to result in failure of the plates or the spacer bars between them. The designs of the cross-sectional area for the outer passageways are dependent upon the temperatures and types of fluids to be passed through the heat exchanger, and the heat exchanger materials which are to be used.

The net elfect is, therefore, that as the temperature in duced stresses are reduced in the plates bordering the outer passageways at each end of the exchanger, the heat exchange efficiency of these outer passageways is reduced below that of a normal heat exchanger, but the design may be such that temperature induced stresses in the plates bordering the intermediate passageways are less likely to reach the limits at which failure of the plates or spacer bars results than in known construe tions in which the outermost passageways are completely blanked off.

In a second embodiment shown in FIGURES 3, 4, and 5 in which parts identical with the exchanger described in the first embodiment are referred to by the same reference numerals, the spacer bars 5 and 7 in the two outermost passageways in the exchanger are eliminated. In this construction, the means for controlling the fluid flow through the outer passageways 4 at a lesser rate than through the intermediate passageways comprises two secondary surface members 10 and 11 disposed respectively in the outermost and next adjacent outer passageways 4. As shown in FIGURE 3, each of the plates 10 and 11 de fines an effective opening for its respective passageway of substantially the same area of that provided by each of the corrugated members 9. However, as shown in FIG- URES 4 and 5, the plate 10 is formed with lines of relatively staggered dimples 12 and in the plate 11 corrugations 13 extend in zig-zag manner from one end of the passageway to the other. The positions of the peaks 13 of the zigzag corrugations is shown diagrammatically in FIGURE 5. The net effect of this is that the area of each plate 10 and 11 for contacting the hot fluid is greater than that for the members 9 while the area provided by plate 10 is greater than the area provided by plate 11. This increases in area effects a greater frictional drag on the fluid than is provided by the members 9 so that flow of fluid through the outermost and next adjacent outer passageways 4 is less than that through the intermediate passageways whereby the heat exchange characteristics in the outer passageways are similar to those described for the first embodiment.

In a third embodiment illustrated in FIGURE 6, parts identical with the exchanger described in the first embodiment are referred to by the same reference numerals.

All of the second series of passageways 4 for hot fluid are provided with corrugated members similar to members 9, between spacer bars 2 and without any restriction being provided for the flow of fluid in the outermost passageways. In the first series of passageways 3 for the cool fluid, the outermost passageways only are provided with corrugated members 9, and the adjacent outer passageways are provided with spacer bars 7 provided with spaced-apart passageway holes 8. The intermediate passageways are provided with spacer bars 5 provided with a plurality of passageway holes 6.

In use of the exchanger the flow of .cool fluid through the intermediate passageways 3 of the first series is less than that through the adjacent outer passageways which, in turn, is less than the flow through the outer passageways. Thus there is progressively more movement of the cool fluid from passageway to passageway in a direction from the intermediate passageways towards the outer passageways. Consequently, there is more heat transfer through the outermost and next adjacent plates so that there is less temperature build up in these plates than the intermeditae plates to obtain temperature induced stresses which are low in the outermost and next adjacent plates.

I claim:

1. A plate-type heat exchanger comprising a plurality of superposed spaced-apart plates, adjacent pairs of plates being separated by spacer bars, the plates and spacer bars defining a first and a second series of passageways, each passageway having an inlet for fluid at one end position and an outlet for fluid at another position, the first series being provided for the passage therethrough of one heat exchange fluid and the second series for the passage therethrough of a relatively hotter heat exchange fluid, the passageways of each series being interposed with passageways of the other series, and fluid flow control means disposed in the first series or second series of passageways, said means comprising fluid-engaging members with fluid flow resistant characteristics which in the outermost passageways of the series differ from those in intermediate passageways of the series to provide in the case where the series is the first series of passageways, a resistance to fluid flow through the outermost passageways which is less than that through intermediate passageways and in the case where the series is the second series of passageways, a resistance to fluid flow through the outermost passageways which is greater than that through intermediate passageways.

2. A plate-type heat exchanger according to claim 1 wherein the members are provided in the first series and members disposed in the outermost passageways of the first series define effective areas of passageway openings which are greater than effective areas of openings for fluid defined in the intermediate passageways of said first series to allow fluid to pass at a greater rate through the outermost passageways.

3. A plate-type heat exchanger according to claim 2 wherein some at least of said members comprise spacer bars disposed between plates of the heat exchanger, the spacer bars having spaced-apart openings therein.

4. A plate-type heat exchanger according to claim 1 wherein said means comprises a member or members disposed in each of the outermost passageways of the first series, the member or members having a surface area for frictionally contacting fluid which is less than that of a member or members disposed in an intermediate passageway of said first series so that fluid is allowed to pass at a greater rate through the outermost passageways.

5. A plate-type heat exchanger according to claim 4 wherein some of said members comprise plates having series of relatively staggered dimples.

6. A plate-type heat exchanger according to claim 4 wherein some of said members comprise plates having corrugations which extend in zig-zag manner along the plates.

7. A plate-type heat exchanger according to claim 1 wherein the members are provided in the second series and members disposed in the outermost passageways of the second series define effective areas of passageways openings which are less than effective areas of openings for fluid in the intermediate passageways of said second series to allow fluid to pass at a lesser rate through the outermost passageways.

8. A plate-type heat exchanger according to claim 7 wherein some at least of said members comprise spacer bars disposed between plates of the heat exchanger, the spacer bars having spaced-apart openings therein.

'9. A plate-type heat exchanger according to claim 1 wherein said means comprises a member or members disposed in each of the outermost passageways of the second series, the member or members having a surface area for frictionally contacting fluid which is greater than that of a member or members disposed in an intermediate passageway of said second series so that fluid is allowed to pass at a lesser rate through the outermost passageways.

10. A plate-type heat exchanger according to claim 9 wherein some of said members comprise plates having series of relatively staggered dimples.

11. A plate-type heat exchanger according to claim 9 wherein some of said members comprise plates having corrugations which extend in zigzag .manner along the plates.

References Cited UNITED STATES PATENTS 2,571,631 10/1951 Trumbler 165166 2,591,878 4/1952 Rogers et al 165166 X 2,596,008 5/1952 Collins 165166 X 3,380,517 4/1968 Butt 165166 MEYER PERLIN, Primary Examiner THEOPHIL W. STREULE, Assistant Examiner 

